Every year, Statbel publishes an update of its vector file of the boundaries of Belgium's statistical sectors on its open data portal.
A statistical sector is the smallest geographical unit used to collect and analyse statistical data. This is a subdivision of a municipality, designed to facilitate demographic, economic and social analyses.
Sh_statbel_statistical_sectors_20240101 includes Belgium's statistical sectors on 01/01/2024. This file is valid until the next modification/correction of the sector boundaries.
A little history:
Belgium was divided into statistical sectors for the first time in the 1970 General Population and Housing Census. This made it possible to obtain a detailed view of the socio-economic realities of the municipalities and to obtain greater precision on the morphology and characteristics of housing.
For more info: statistical sectors